The train and the tunnel

A train that is 500 meters long travels at half a kilometer per minute and goes through a tunnel 500 meters long.

How long will it take to completely cross the tunnel?

Solution

Its speed is half a kilometer per minute = 500m per minute. The first minute enters whole and the second minute leaves whole or another explanation the 500m train plus the 500m tunnel gives a kilometer that the train has to travel if it goes at 500m per minute it will take two minutes in finishing.